Spark plug



April 1 1924.

W. D. SKELTON ET AL SPARK PLUG Filed July 19. 1921 have 0. kS/rozzvn a m7 um I a Patented 1, 19 24. 4

UNITED STATES 1,489,162 PATENT OFFICE.

WARREN D. SKEL'ION AND mama's H. HAYES, OF THERHOPOLIS, WYOMING.

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Application filed mils,

To all whom it may concern:

Be it known that we, WARREN D. Sm TON and CHARLES H. Harms, citizens of the United States, residing at Thermogplls, in the county of Hot Springs and ate of, Wyoming, have invented certain new and useful Improvements in Spark Plugs, of which the following is a specification.

This invention has for its object to provide a strong, durable and leak roof spark plug, and also one which is simp e and inexensive in construction, the parts employed Being few and capable of being readily assembled.

The invention also has for its object to provide a spark plug having a novel and im-- proved insulating core for the main center electrode, together with other novel and improved features of construction to be described in detail hereinafter.

In order that the invention may be better understood, reference is had to the accompanying drawing, wherein- Figure 1 is an elevation of the plug, and Figure 2 is a central section thereof.

Referring specifically to the drawing, the body of the plug is composed of two axially alined sections 5 and 6, the former bein a metallic base shell having a reduced an screw-threaded end portion 7 so that it may be screwed into the s ark-plug opening of the engine cylinder. e section 6, which is at the outer end of the plug body, is made of fiber or other suitable non-conductive material. The c linder end 7 of the plu is fitted with t e usual side electrode 8 which has a lateral bend to terminate adjacent to the cylinder end of the main central electrode rod 9 of the plug.

The end of the plu section 5 to which the section 6 is connecte has a reduced central rearward extension 10 which is externally screw-threaded, and the section 6 has a screw-threaded opening 11 of corresponding diameter so that it may be screwed on said extension. Between the outer end of the extension 10 and the opposite end of the opening 11 is interposed a gasket 12.

The extension 10 produces a shoulder 13 on the outer end of the section 5, opposite which shoulder the inner end of the section 6 is located, said shoulder havin an inward bevel 0r slope, and the end of t e section 6 being correspondin 1y .beveled. Between the shoulder 12 an the inner end of the section 6 is interposed a gasket 13.

PLUG.

1921. Serial No. 485,915.

The interior of the section 5 contains a core 14 of non-conductive material through which the electrode 9 passes and in which it is rigidly embedded. This core is flush with the cylinder end 7 of the section 5, and

the electrode 9 protrudes therefrom to terminate adjacent to the side electrode 8. The bore of the section 5 containing the core 14 is reduced in diameter near its upper end to form a shoulder 15, and the core is correspondingly shouldered to abut'against this nut and the end of the section 6. That portion-of the electrode 9 which is embedded in the core 14 has a lateral bend or offset 19, and the threaded portion of the electrode also extends part wa into the core, whereby the electrode is fi y held in the core.

The insulating core 14 is formed of a plastic composition which is a non-conductor of electricity, heat and moisture, and which is capable of successfully withstanding severe shocks from the com ression and explosions in the cylinder. he electrode 9 is laced in 'a mass of this com osition before 1t has set, and the mass is orced into the interior of the section 5 until the same, as well as the extension 10, are completely filled, and while under pressure the mass is heated until it becomes dry and hard, whereupon it adheres firmly to the interior of the section 5 and to the embedded electrodes. The core is flush withthe cylinder end 7 of the section 5, producing here a smooth surface which can be easily cleaned, and which does not permit oil and carbon to collect upon and around the electrodes 8 and 9. The compressions and explosions in the cylinder have a tendency to keep the plug end clean of carbon and oil.

The outer section 6ofthe plug bod is made in one piece of condensed vulcanize fiber, or other suitable material which is a non-conductor of electricity, heat and moisture, and

i or other moisture splashes against the same.

This trouble is entirely eliminated by enclosing the core 14 as shown. The section 6 also prevents damage of the core 14 when changing plugs. Plugs having an exposed porcelain very frequently are damaged by the wrench or other tool slipping and Stllkin the same.

We claim:

A spark plug comprising a metallic shell having its upper end provided with a reduced and externally threaded neck and an annular shoulder about the base of the neck, the walls of the neck bein prqected inwardly to provide an interna abutment shoulder, a protecting body of water roof insulating material having a pocket sadmg from its lower end and havin threaded wa ls for engaging the threads 0 said neck to removably retain the body upon the neck with its inner end engaging the external abutment shoulder about the base of the neck, a central electrode extendin longitudinall through said shell and avin a three ed upper end portion exten ing through said body and beyond its upper end, insulating material filling the interiol of said shell about said electrode, and feetener means screwed upon the extended upper end of said electrode.

In testimony whereof we alfix our signatures. i

WARREN D. SKELTON. CHARLES H. HAYES. 

